On kenmore canister Vacs there are two type of power switches. There are those on the cannisters themselves and those on the handle. Access on the handle is achieved by dissassembling the handle itself. Check the wiring harness because, it may be the wiring harness is shorted. The one on the cannister (If the symbol on the cannister button is a Cord Plug and not a 1 in a circle, It's on the handle,) can be accessed by taking the bag lid off and removing the 4 screws, The switch snaps in to the housing cover.
Alexander 24, Maryland, December 2006